The official campaign to leave the EU is offering voters the chance to win £50 million if they can correctly guess the outcome to every game at Euro 2016.

The competition, which was launched by Vote Leave on Friday, is urging adults across the country to sign up regardless of how they will vote in the referendum

Should no one guess all the results – a near certainty given odds of a billion to one according to bookmakers – the person who calls the outcome of most games correctly will get £50,000.

Out campaign sources said the stunt was a way to highlight how much Britain was giving to the EU every day - £50 million - and get people talking about the referendum.

However critics questioned whether the competition was a clever way of getting voters' data ahead of the final four weeks of the referendum campaign.

Terms and conditions detailed on the competition's website reveal that data put in by those taking part will be used for funding raising by the Out campaign.

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Information provided will be used to “keep you up to date with the campaign”, “offer you opportunities to engage with our activities” and “conduct fundraising activities”, competitors are told in the small print.

The Out campaign believes it is at a disadvantage to the pro-EU side because it does not have access to data on voters held by leading political parties.

The competition is based on a similar venture run by Warren Buffett based on “March Madness” basketball in America.

To win the £50 million prize, punters will have to correctly guess the result of every European Football Championships this summer. Just the result – a win, loss or draw - and not the score is needed.

Should no one win, £50,000 will be given to the person who got the highest number of correct results in a row. The funds will come from insurance rather than donations, according to Vote Leave.

The announcement read: “The competition is open to any member of the public who is over the age of 18 and is registered to vote in the EU referendum.

“How someone votes in the referendum or whether they even vote is irrelevant to whether they can enter and win.”

Vote Leave’s Campaign Director, Dominic Cummings, said: “This is the chance of a lifetime - just imagine what you could do with the £50 million we send to the EU every single day.

"We want everyone to have the chance to win the sort of money most people can only dream of, unless they are a banker or a Euro MP.

“Too many people, particularly younger voters, don’t engage in politics and do not plan to vote in the referendum. For years there’s been a lot of talk about this problem but it’s got worse.

"50million.uk is an attempt to engage with large numbers of people who normally ignore politics. We’ll be able to speak to them about the issues, give them some facts, and answer their questions.”

A spokesman for Paddy Power said the odds of winning the £50 million prize was a billion to one. (The odds of the Loch Ness Monster being discovered this year are 500/1).

"I thought predicting England’s strike partnership was going to be difficult this summer but this takes the biscuit," the spokesman said.

"There’s a billion in one chance of getting this right so you might be better off putting a few quid on Boris to be on the front of Playboy.”